    /****************************************************************************
    **
    ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
    ** All rights reserved.
    ** Contact: Nokia Corporation (qt-info@nokia.com)
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL$
    ** GNU Lesser General Public License Usage
    ** This file may be used under the terms of the GNU Lesser General Public
    ** License version 2.1 as published by the Free Software Foundation and
    ** appearing in the file LICENSE.LGPL included in the packaging of this
    ** file. Please review the following information to ensure the GNU Lesser
    ** General Public License version 2.1 requirements will be met:
    ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
    **
    ** In addition, as a special exception, Nokia gives you certain additional
    ** rights. These rights are described in the Nokia Qt LGPL Exception
    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
    ** GNU General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU General
    ** Public License version 3.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of this
    ** file. Please review the following information to ensure the GNU General
    ** Public License version 3.0 requirements will be met:
    ** http://www.gnu.org/copyleft/gpl.html.
    **
    ** Other Usage
    ** Alternatively, this file may be used in accordance with the terms and
    ** conditions contained in a signed written agreement between you and Nokia.
    **
    **
    **
    **
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/
     
    #ifndef GLEXTENSIONS_H
    #define GLEXTENSIONS_H
     
    #include <QtOpenGL>
     
    /*
    Functions resolved:
     
    glGenFramebuffersEXT
    glGenRenderbuffersEXT
    glBindRenderbufferEXT
    glRenderbufferStorageEXT
    glDeleteFramebuffersEXT
    glDeleteRenderbuffersEXT
    glBindFramebufferEXT
    glFramebufferTexture2DEXT
    glFramebufferRenderbufferEXT
    glCheckFramebufferStatusEXT
     
    glActiveTexture
    glTexImage3D
     
    glGenBuffers
    glBindBuffer
    glBufferData
    glDeleteBuffers
    glMapBuffer
    glUnmapBuffer
    */
     
    #ifndef Q_WS_MAC
    # ifndef APIENTRYP
    #   ifdef APIENTRY
    #     define APIENTRYP APIENTRY *
    #   else
    #     define APIENTRY
    #     define APIENTRYP *
    #   endif
    # endif
    #else
    # define APIENTRY
    # define APIENTRYP *
    #endif
     
    #ifndef GL_VERSION_1_2
    #define GL_TEXTURE_3D 0x806F
    #define GL_TEXTURE_WRAP_R 0x8072
    #define GL_CLAMP_TO_EDGE 0x812F
    #define GL_BGRA 0x80E1
    #endif
     
    #ifndef GL_VERSION_1_3
    #define GL_TEXTURE0 0x84C0
    #define GL_TEXTURE1 0x84C1
    #define GL_TEXTURE2 0x84C2
    #define GL_TEXTURE_CUBE_MAP 0x8513
    #define GL_TEXTURE_CUBE_MAP_POSITIVE_X 0x8515
    //#define GL_TEXTURE_CUBE_MAP_NEGATIVE_X 0x8516
    //#define GL_TEXTURE_CUBE_MAP_POSITIVE_Y 0x8517
    //#define GL_TEXTURE_CUBE_MAP_NEGATIVE_Y 0x8518
    //#define GL_TEXTURE_CUBE_MAP_POSITIVE_Z 0x8519
    //#define GL_TEXTURE_CUBE_MAP_NEGATIVE_Z 0x851A
    #endif
     
    #ifndef GL_ARB_vertex_buffer_object
    typedef ptrdiff_t GLsizeiptrARB;
    #endif
     
    #ifndef GL_VERSION_1_5
    #define GL_ARRAY_BUFFER 0x8892
    #define GL_ELEMENT_ARRAY_BUFFER 0x8893
    #define GL_READ_WRITE 0x88BA
    #define GL_STATIC_DRAW 0x88E4
    #endif
     
    #ifndef GL_EXT_framebuffer_object
    #define GL_RENDERBUFFER_EXT 0x8D41
    #define GL_FRAMEBUFFER_EXT 0x8D40
    #define GL_FRAMEBUFFER_COMPLETE_EXT 0x8CD5
    #define GL_COLOR_ATTACHMENT0_EXT 0x8CE0
    #define GL_DEPTH_ATTACHMENT_EXT 0x8D00
    #endif
     
    typedef void (APIENTRY *_glGenFramebuffersEXT) (GLsizei, GLuint *);
    typedef void (APIENTRY *_glGenRenderbuffersEXT) (GLsizei, GLuint *);
    typedef void (APIENTRY *_glBindRenderbufferEXT) (GLenum, GLuint);
    typedef void (APIENTRY *_glRenderbufferStorageEXT) (GLenum, GLenum, GLsizei, GLsizei);
    typedef void (APIENTRY *_glDeleteFramebuffersEXT) (GLsizei, const GLuint*);
    typedef void (APIENTRY *_glDeleteRenderbuffersEXT) (GLsizei, const GLuint*);
    typedef void (APIENTRY *_glBindFramebufferEXT) (GLenum, GLuint);
    typedef void (APIENTRY *_glFramebufferTexture2DEXT) (GLenum, GLenum, GLenum, GLuint, GLint);
    typedef void (APIENTRY *_glFramebufferRenderbufferEXT) (GLenum, GLenum, GLenum, GLuint);
    typedef GLenum (APIENTRY *_glCheckFramebufferStatusEXT) (GLenum);
     
    typedef void (APIENTRY *_glActiveTexture) (GLenum);
    typedef void (APIENTRY *_glTexImage3D) (GLenum, GLint, GLenum, GLsizei, GLsizei, GLsizei, GLint, GLenum, GLenum, const GLvoid *);
     
    typedef void (APIENTRY *_glGenBuffers) (GLsizei, GLuint *);
    typedef void (APIENTRY *_glBindBuffer) (GLenum, GLuint);
    typedef void (APIENTRY *_glBufferData) (GLenum, GLsizeiptrARB, const GLvoid *, GLenum);
    typedef void (APIENTRY *_glDeleteBuffers) (GLsizei, const GLuint *);
    typedef void *(APIENTRY *_glMapBuffer) (GLenum, GLenum);
    typedef GLboolean (APIENTRY *_glUnmapBuffer) (GLenum);
     
    struct GLExtensionFunctions
     {
            bool resolve(const QGLContext *context=0);
     
        bool fboSupported();
        bool openGL15Supported(); // the rest: multi-texture, 3D-texture, vertex buffer objects
     
            _glGenFramebuffersEXT GenFramebuffersEXT;
            _glGenRenderbuffersEXT GenRenderbuffersEXT;
            _glBindRenderbufferEXT BindRenderbufferEXT;
            _glRenderbufferStorageEXT RenderbufferStorageEXT;
            _glDeleteFramebuffersEXT DeleteFramebuffersEXT;
            _glDeleteRenderbuffersEXT DeleteRenderbuffersEXT;
            _glBindFramebufferEXT BindFramebufferEXT;
            _glFramebufferTexture2DEXT FramebufferTexture2DEXT;
            _glFramebufferRenderbufferEXT FramebufferRenderbufferEXT;
            _glCheckFramebufferStatusEXT CheckFramebufferStatusEXT;
     
            _glActiveTexture ActiveTexture;
            _glTexImage3D TexImage3D;
     
            _glGenBuffers GenBuffers;
            _glBindBuffer BindBuffer;
            _glBufferData BufferData;
            _glDeleteBuffers DeleteBuffers;
            _glMapBuffer MapBuffer;
            _glUnmapBuffer UnmapBuffer;
    };
     
    inline GLExtensionFunctions &getGLExtensionFunctions()
     {
            static GLExtensionFunctions funcs;
            return funcs;
    }
     
    #define glGenFramebuffersEXT getGLExtensionFunctions().GenFramebuffersEXT
    #define glGenRenderbuffersEXT getGLExtensionFunctions().GenRenderbuffersEXT
    #define glBindRenderbufferEXT getGLExtensionFunctions().BindRenderbufferEXT
    #define glRenderbufferStorageEXT getGLExtensionFunctions().RenderbufferStorageEXT
    #define glDeleteFramebuffersEXT getGLExtensionFunctions().DeleteFramebuffersEXT
    #define glDeleteRenderbuffersEXT getGLExtensionFunctions().DeleteRenderbuffersEXT
    #define glBindFramebufferEXT getGLExtensionFunctions().BindFramebufferEXT
    #define glFramebufferTexture2DEXT getGLExtensionFunctions().FramebufferTexture2DEXT
    #define glFramebufferRenderbufferEXT getGLExtensionFunctions().FramebufferRenderbufferEXT
    #define glCheckFramebufferStatusEXT getGLExtensionFunctions().CheckFramebufferStatusEXT

    #define glActiveTexture getGLExtensionFunctions().ActiveTexture
    #define glTexImage3D getGLExtensionFunctions().TexImage3D
     
    #define glGenBuffers getGLExtensionFunctions().GenBuffers
    #define glBindBuffer getGLExtensionFunctions().BindBuffer
    #define glBufferData getGLExtensionFunctions().BufferData
    #define glDeleteBuffers getGLExtensionFunctions().DeleteBuffers
    #define glMapBuffer getGLExtensionFunctions().MapBuffer
    #define glUnmapBuffer getGLExtensionFunctions().UnmapBuffer
     
    #endif
